package com.example.leonard.core.domain;

import java.io.PrintStream;

/**
 * @auther heyang
 * @date 2021/3/26 23:09
 */
public class demo {
    public static void main(String[] args) {
        if (System.out.printf("A")==null) {
            System.out.println("A");
            PrintStream a = System.out.printf("A");
        } else {
            System.out.println("B");
        }
    }
}
